改了配置文件，运行中的程序为什么没有变？

import json
from dataclasses import dataclass


@dataclass(frozen=True)
class Config:
    timeout_ms: int
    page_size: int


def parse_config(text):
    data = json.loads(text)
    if type(data) is not dict or set(data) != {"timeout_ms", "page_size"}:
        raise ValueError("必须恰好提供 timeout_ms 和 page_size")
    for name, maximum in (("timeout_ms", 30000), ("page_size", 100)):
        if type(data[name]) is not int or not 1 <= data[name] <= maximum:
            raise ValueError(f"{name} 必须是 1 到 {maximum} 的整数")
    return Config(**data)


def reload_config(active, text):
    try:
        candidate = parse_config(text)
    except json.JSONDecodeError:
        print("重载拒绝: JSON 格式错误")
        return active
    except ValueError as error:
        print("重载拒绝:", error)
        return active
    return candidate


def main():
    text = '{"timeout_ms": 1000, "page_size": 20}'
    active = parse_config(text)
    old_request = active
    print("启动读取:", active)

    text = '{"timeout_ms": 300, "page_size": 50}'
    print("只改文本:", active)
    active = reload_config(active, text)
    print("重载成功:", active)
    print("旧请求仍用:", old_request)

    active = reload_config(active, '{"timeout_ms": 0, "page_size": 50}')
    print("校验失败后:", active)
    active = reload_config(active, '{')
    print("解析失败后:", active)


if __name__ == "__main__":
    main()